1. Field of the Invention
The present invention relates generally to Push-To-Talk (PTT) voice communications, and more particularly to methods and apparatus for the immediate acceptance and queuing of voice data for PTT voice communications.
2. Description of the Related Art
A wireless communication device, such as a cellular telephone or mobile station, is capable of making and receiving voice calls and/or sending and receiving data over a wireless communication network. Recent developments have given such mobile stations the ability to communicate in “push-to-talk” (PTT) modes using Push-to-talk over Cellular (PoC) technology. PoC communication utilizes Voice-over-IP (VoIP) techniques which involve the communication of data packets carrying voice information. PoC communication is adapted for one-to-one talks or group talks which are session-based. The end user of a mobile station may send an “invitation” for PoC communication to other potential “participants” who may “accept” or ignore the invitation. When an initiation is accepted, a PoC session is created between the two participants. Further acceptances of the invitation may expand the session into a group session having more than two participants.
In such networks, when the PTT switch is pressed at the mobile station, the end user is not able to immediately speak into the microphone. The end user must wait for some time delay period after the PTT switch depression in order to speak. This time delay period may be caused by PTT setup and channel setup activities. This delay is an inconvenience for end users in PTT communications, who may have to wait up to around eight seconds in some cases to talk after depressing the PTT switch.
In proposed Global System for Mobile communications (GSM) standards, buffering in the network is suggested to work-around the connection delay while the base station is paging the other party (or parties). However, no such technique is described for the handset to allow the origination party to talk immediately after PTT switch actuation. The following is text from the GSM standard that addresses the issue between the base station and a “user B”, which does not address the issue between a “user A” and the base station:                If the PoC server is configured to use the optional early media procedures, it will answer the INVITE with a 202 (Accepted) response. This response together with the “floor grant” message from the talker arbitration process informs user A that user B has not been reached yet, but that the PoC server is already prepared to receive media. The PoC server will buffer all the media received from user A until it can be delivered to user B. When user B is finally contacted, the PoC server informs user A about this using a NOTIFY request.        A network support early media establishment shall be prepared to receive media prior to any invited user answers and shall buffer received media until at least the first invited user accepts the invitation. The buffered media should be sent to all users that accept the invitation. The media establish mode to operate is implementation dependent, however, the PoC server may use e.g. a pre-configured network parameter, a property of the user of a property of the group. The amount of the media that the network may buffer until the first invited user accepts the invitation is a network option.        
Again, these techniques relate to buffering in the network and do not address the time delay between PTT switch actuation and the time to begin talking. Note there is a gap in this technique even for some of the user B's communications. The network only buffers media until the first user B is accepted, and the buffered media are sent to all users that accepted. Thus, some middle portion of the voice data may be missed for users 2 to N.
Accordingly, there is a resulting need for mobile station methods and apparatus for facilitating PTT voice communications that overcome the deficiencies of the prior art.